cat by pass

ratboy01

ratboy01

Forum Member
Joined
Nov 23, 2013
Messages
59
Location
west bromwich
has anyone ever taken off both there catalytic converters? and if so did you encounter any runing problems?
mine is a 98 my 2ltr n/a
 
Gidday RatBoy & B25

I don't know what the long term effects will be either.
However, the engine is designed to run with these installed, so one should think about that.

There are also issues regarding the vehicle being unroadworthy if its emission control systems have been interfered with or modified in any way.

Just a few thoughts, FWIW.
 
Why would you bother? As for the long term affects- depending on the model, they are there to help the ECU run the engine if they have sensors there. They may affect how rich the engine runs. Too lean may mean a blown engine. Too rich and the engine wears out prematurely. There are better ways of improving their efficiency. A broom handle comes to mind if you are that keen. I put a new high flow cat on my WRX and picked up 20kw ATW, and the car sounds better too! Depending on what state you are in, in Australia, there are potentially huge fines for not having a cat- up to $10,000 in NSW if you are very unlucky. Which is interesting because if you have a factory in Mulgrave NSW spewing out chemicals over at least 3 suburbs which are so obnoxious you feel sick, the EPA will have a chat and ask you to fix it some time in the next 18 months if you have the time and if it is not too much trouble- they sure as hell won't fine you.
 
^ Thanks for that insight, Rally. I knew that there would be some ramifications.

Agree about the EPA and pollution generally. Same here in Victoria.

It's enough to make you sick.
Hang about - it DOES make us sick!
And the planet too.
 
If you go to OzFoz there's a lot of people who remove the front cat but they have to retune the ECU. As Rally mentioned, sensors are involved. In particular, Throttle Happy seems to know a lot about these mods & does tunes for people. I'm sure they do the same on RexNet.

Also as Rally said, very large fines can be handed out for removing cats. Some people keep the cat but strip it inside to improve the flow while keeping the appearance of a cat but again this is illegal so you didnt hear it from me lol :lol:
 
Been there with other cars and welded pipe through the cat, performance gains need to be tuned, the extra noise with a performance exhaust gives you a headache before the car leaves the driveway.


EDIT: put my head under the car and had a look/ pulled out the shop manual :The o2 sensor is on the first cat the second rear cat has no sensor on 97SF5 (mine has the a 2 /14" exhaust from the first cat straight through with a hot dog and high flow muffler). Can remove the rear cat no worries mine still checks for fine for emissions(mainly a noise/eu emissions thing), a good exhaust shop will check all that for you. A reset of the ecu and it can compensate for this setup in mine, there's a little economy increase. I didn't notice any performance increase besides climbing hills a little better off road. I replaced the exhaust because i damaged it and the sports exhaust was 1/4 the price of the Subaru one, otherwise i probably wouldn't bother unless your doing it in conjunction with other performance mods. Alone it just makes the car sounds like its going 3 times as fast as it actually is

My first exhaust before i had the hotdog put in had a terrible drone at 3,000rpm which was exactly where the engine sits on the freeway
 
Last edited:
im in england, removing the cat just voids the mot, tbhafter reading this, i was thinking of leaving the front cat on. but scrapping the rear as its in a very bad way. and i belive might be brocken up inside.
but thanks for the input and i will post up how i get on with it.
i have done this with a cadillac i owned a few years back with no problems at all, but subarus are still new to me.
 
You must log in or register to reply here.
Back
Top